Polyamide resins are widely used in hot melt coating and adhesive applications. However, polyamide coatings cannot be bonded directly to certain substrates, such as metal substrates while at the same time providing all of the desired properties for such compositions. Hence, it is desired that adhesive compositions exhibit uniformly sharp melting points, good moisture vapor barrier properties, good chemical, solvent and product resistance, excellent adhesion to a wide variety of surfaces such as treated and untreated polyolefin and polyester films, paper, aluminum foil, as well as metals. In addition, such coatings should exhibit good compatability with other film forming resins, tackifiers, and plasticizers while at the same time exhibit flexibility combined with toughness.
Although as of the present time various attempts have been made to incorporate various polyolefins into polyamide resin adhesive compositions to improve some of the aforementioned properties, in general, the art has been deficient in providing compatible admixtures of polyamide resin compositions with polyethylenes. Blends of these materials have been known to be low key in appearance when hot and produce brittle and grainy films upon cooling and, hence, it has been impractical to produce useful hot melt coating and adhesive compositions and the like, based on such blends.